System for controlling articulation forces

Abstract

In some aspects, a control algorithm is provided for manipulating a pair of articulation arms configured to control an articulation angle of an end effector of a robotic surgical instrument. Other aspects of the present disclosure focus on the robotic arm system, including the pair of articulation arms coupled to the end effector and guided by independent motors controlled by a control circuit. Each of the articulation arms are designed to exert antagonistic forces competing against each other that are apportioned according to a ratio specified in the control algorithm. The ratio of the antagonistic forces may be used to determine the articulation angle of the head or end effector of the robotic surgical arm.

The invention claimed is: 
     
       1. A system for a robotic surgical instrument, the system comprising:
 a control circuit; 
 a first motor and a second motor, both communicatively coupled to the control circuit; 
 a first articulation arm communicatively coupled to the first motor; 
 a second articulation arm communicatively coupled to the second motor; and 
 an end effector coupled to the first articulation arm via a first hinge and the second articulation arm via a second hinge; 
 wherein:
 the control circuit is configured to cause the first motor to apply a first force to the first articulation arm; 
 the control circuit is configured to cause the second motor to apply a second force to the second articulation arm, wherein the second force is antagonistic to the first force such that the first and second forces apply counteracting forces at the end effector; 
 the first and second forces cause the end effector to articulate via the first and second hinges; and 
 the end effector is configured to articulate to a prescribed angle based on a ratio of magnitudes between the first force and the second force. 
 
 
     
     
       2. The system of  claim 1 , further comprising an articulation pivot coupled to the end effector, wherein the end effector is further configured to articulate about the articulation pivot. 
     
     
       3. The system of  claim 2 , wherein the articulation pivot is positioned off of a center axis running longitudinally in between and equidistant from at least a portion of the first and second articulation arms. 
     
     
       4. The system of  claim 2 , further comprising a shaft encapsulating the first and second articulation arms. 
     
     
       5. The system of  claim 4 , further comprising a pivot link coupled to the articulation pivot and stably positioned within the shaft, wherein the pivot link is configured to stabilize the end effector while the end effector articulates about the articulation pivot. 
     
     
       6. The system of  claim 5 , wherein the pivot link and the articulation pivot are positioned off of a center axis running longitudinally in between and equidistant from at least a portion of the first and second articulation arms. 
     
     
       7. The system of  claim 6 , wherein the first force is greater than the second force when the end effector is articulated to a zero degree angle from a center position. 
     
     
       8. The system of  claim 1 , wherein the control circuit is configured to operate the first motor independent of the second motor. 
     
     
       9. The system of  claim 1 , wherein the first and second forces are pulling forces applied to the first and second articulation arms, respectively. 
     
     
       10. The system of  claim 1 , wherein the first and second forces are pushing forces applied to the first and second articulation arms, respectively. 
     
     
       11. A method of a robotic surgical instrument comprising a control circuit, a first motor, a second motor, a first articulation arm, a second articulation arm, and an end effector, the method comprising:
 instructing, by the control circuit, the first motor to apply a first force to the first articulation arm; 
 instructing, by the control circuit, the second motor to apply a second force to the second articulation arm, wherein the second force is antagonistic to the first force such that the first and second forces apply counteracting forces at the end effector; and 
 causing the end effector to articulate to a prescribed angle via first and second hinges, based on the first and second forces applied to the first and second articulation arms, respectively, and based on a ratio of magnitudes between the first force and the second force. 
 
     
     
       12. The method of  claim 11 , wherein the robotic surgical instrument further comprises an articulation pivot coupled to the end effector, wherein the end effector further articulates about the articulation pivot. 
     
     
       13. The method of  claim 12 , wherein the articulation pivot is positioned off of a center axis running longitudinally in between and equidistant from at least a portion of the first and second articulation arms. 
     
     
       14. The method of  claim 12 , wherein the robotic surgical instrument further comprises a shaft encapsulating the first and second articulation arms. 
     
     
       15. The method of  claim 13 , wherein the first force is greater than the second force when the end effector is articulated to a zero degree angle from a center position. 
     
     
       16. The method of  claim 11 , wherein applying the first force from the first motor is independent of applying the second force from the second motor. 
     
     
       17. The method of  claim 11 , wherein the first and second forces are pulling forces applied to the first and second articulation arms, respectively. 
     
     
       18. The method of  claim 11 , wherein the first and second forces are pushing forces applied to the first and second articulation arms, respectively.